Membrane preparation sulfonate form

Great improvements in the TFC membranes were also experienced by Chen et al. [56] by incorporating water-soluble amine reactants—sulfonated cardo poly(arylene ether sulfone) (SPES-NH2)—into an aqueous solution containing MPD. Under optimum preparation conditions, the TFC membranes prepared from SPES-NH2 showed remarkable increase in water permeability (51.2 L/m h) with a slight decrease in salt rejection (97.5% at 2000 ppm NaCl, 2 MPa) compared to membranes prepared without SPES-NH2 (37.4 L/m h and 99%). The improved results are attributed to the incorporation of hydrophilic SPES-NH2 to PAs and/or a higher degree of cross-linking formed in the thin selective layer. In view of the importance of hydrophilicity on TFC membrane performance, a novel amine monomer—3,5-diamino-A-(4-aminophenyl) benzamide (DABA)—with three amino... 

A suitable polymer material for preparation of carbon membranes should not cause pore holes or any defects after the carbonization. Up to now, various precursor materials such as polyimide, polyacrylonitrile (PAN), poly(phthalazinone ether sulfone ketone) and poly(phenylene oxide) have been used for the fabrication of carbon molecular sieve membranes. Likewise, aromatic polyimide and its derivatives have been extensively used as precursor for carbon membranes due to their rigid structure and high carbon yields. The membrane morphology of polyimide could be well maintained during the high temperature carbonization process. A commercially available and cheap polymeric material is cellulose acetate (CA, MW 100 000, DS = 2.45) this was also used as the precursor material for preparation of carbon membranes by He et al They reported that cellulose acetate can be easily dissolved in many solvents to form the dope solution for spinning the hollow fibers, and the hollow fiber carbon membranes prepared showed good separation performances. 

Sulfonation can be avoided, by using low temperatures, e.g., 15 °C [54], However, only dilute PEEK solutions can be formed in the concentrated sulfuric acid at low temperatures. Another approach is to use non-sulfonating acid solvents, such as methane-sulfonic acid and trifluoromethanesulfonic acid [10]. An alternative to acid-based solvent systems for PEEK membrane preparation involves the use of high-boiling point solvents and plasticizers that dissolve the PEEK at elevated temperatures. The solubility of 104 different solvents is presented in the literature [55],... 

Bikson, B. and Nelson, J.K., Fluid Separation Composite Membranes Prepared from Sulfonated Aromatic Polymers in Lithium Salt Form US 5364454, 1994. (Praxair Technology Corp.)... 

Bikson B, Nelson JK. Fluid separation composite membranes prepared from sulfonated aromatic polymers in lithium salt form. US Patent 5,364, 454 (1994). 

---